Motor vehicle



March 9, 1937. F. ROL'LER MOTOR VEHICLE Filed March 11, 1935 r 0 LL n ew "J Patented Mar. 9, 1937 I UNITED STATES MOTOR VEHICLE Franz Roller,

Stuttgart, Germany, assignor to Daimler Benz Aktienge'sellschaft,Stuttgart- Unterturkheim, Germany Application March 11, 1935, Serial No.10,549

v In Germany March 15, 1934 I'Claim.

This invention relates to driving means for motor vehicles, moreparticularly those with two or more driven axles and a differentialarrangement for distributing the driving torque, and consistssubstantially in this that the diiferential arrangement transmits thedriving torque to one part of the drive, more particularly to the wheelsof one axle a difierent torque from that which it transmits to anotherpart of the drive, more particularly to the Wheels of another axle orother axles. This arrangement makes possible a very good utilization ofthe adhesion of the wheels through adapting the power transmission tothe loads on the wheels or the axles. Suitably this result is obtainedin the case of bevel wheel differential gears through the bevel wheelswhich dis,- tribute the driving torque having different transmissionratios or different cone angles. transmission ratios may be constant orvariable. Where there are more than two driven axles, a difierential maybe disposed between each two axles. A very complete adaptation of thedriving torque to the loads can be realized, if, besides thedifferential gears for the distribution (more particularly unequaldistribution) of the torque to the individual pairs of wheels or wheelaxles, there are also provided between the wheels of each pair of wheelsdiiierential gears for the distribution (more particularly unequaldistribution)'of the torque.

In the accompanying drawing some constructional examples of theinvention are illustrated: Figs. 1 and '2 show two possible arrangementsof the drive of an eight-wheel vehicle.

. Fig. 3 shows a four-wheel drive.

Fig. 4 shows the difierenti a larger scale, and

Figs. 5 and 6 are two diagrammatic views for explaining the mode ofoperation of the differential gear. Y In Fig. 1 dis the motor, I) thecoupling, 0 the change'speed gear, d1: the differential gear whichdistributes the drive on the one hand'to the front wheels I and on theother hand to the six rear wheels 2, 3 and 4. The drive of the frontwheels I is through the differential gear 111. In front of the axle ofthe wheels 2 is afurther difierential gear (123, which transmits thedrive on the one hand through the differential gear d2 to the wheels 2and on the other hand to the rearmost wheels 3 and 4. Similarly thedifferential gear (134 is provided for driving the wheels 3 through thedifferential gear (is and the wheels 4 through the. difier'ential geard4. Thus with altogether 55 eight driven wheels there are sevendifferential a1 gear of Fig. to

The

gears or generally with n driven wheels n-'1 differential gears. Thedifferential gears d12, (Z2: and (134 are suitably so constructed thatthe driving torquedistributes itself to the individual axles accordingto the loadacting on them. Such a construction of the individualdifferential gears disposed between the axles is of course also ofadvantage, when separate differential gearsiare not provided between theindividual wheels :of each axle. In the kind of drive illustrated thedrive for the individual axles is branched off from a central drivingline of shafting in the sequence in which they are arranged. Thedistribution of the drive might however be effected in a difierentmanner, for instance through the drive being first distributed to eachof twoaxles and thereupon each branch drive being divided up again toeach of the two axles associated with it, as shown by way of example inFig. 2, where the drive of the motor is distributed through thedifferential gear (123 simultaneously to the differential gears (112 and1234. The axles may be rigid axles, swinging axles or-the like.

Fig. 3 shows the constructional form of a four- I wheel driveaccordingto'the invention. The motor which is not shown isfixed by flanges (Fig.3 to the right) to the casing e which contains the change speed gear cand the differential gear d2 for the rear axle.

This casing forms a partof the vehicle frame and is continued by theadjoining casingfor the differential-gear diz and-the tube j whichconnects the drive casing with the front axlecasing g. In detail thedrive is effected by the engine shaft h which extends over and beyondthe rear axle and is adapted to be coupled with'the main .shaft 1' ofthe gear through a change over con-- pling k. The two hollow shafts land m act as countershafts for the change speed 'gear, the arrangementbeing such that the shaft '1 can be coupled on the one hand through thepermanently meshing pair of toothe'dxwheelsn by way of the coupling iswith the shaft h and on the other hand through the permanently meshingpair of toothed wheels 0 with the main shaft 2 of the' Y gear. Thecountershaft m is further capable of being coupled in the usual waythroughslidable wheels p'with the main shaft 2 of the gear. Furthercoupling means q are also provided between'theshafts l and m I Thecountershaft m is rigidly connected to the differential casing (Z12. Inthis casing is mounted the transverse pin 1', on which are rotatable thelarger bevel wheels s-fo'r driving the bevel wheel t and the smallerbevel wheels u for driving the bevel wheel 12. The bevel wheels s and uare in each case rigidly connected together to form a pair. The bevelwheel 7? serves for driving the shaft w leading to the front axle andthe bevel wheel 12 for driving the shaft :1: leading to the rear axle.

'According to the invention, more particularly as shown in Fig. 4, theteeth of the bevel wheels of the differential gear are so selected thatthe semi-vertical angle a of the bevel wheels s and t is greater thanthe semi-vertical angle of p of the bevel wheels u and 'v. The powerratios shown in Figs. 5 and 6 are thus obtained, in which the bevelwheels are replaced by similarly acting differential levers. Fig. 6shows the two-armed differential lever s-u in plan view. Ts, n, Tu andTv signify the radii at which the periferal forces of the toothed wheelsor levers produce a rotary motion of the same, while rirepresents thelever arm, with which the differential body d1: drives levers s-u aroundthe axis of the shafts w and at.

On the lever s-u of Figs. 5 and 6 (or the corresponding pair of toothedwheels of Fig. 4) being driven by the force R in the direction of thisforce, the said lever will'move along evenly, without turning forinstance around the pin 1', when the lever forces S and U are inequilibrium in accordance with the lever principles. The levers t and vor the wheels t and 12 will consequently be turned (the pair of leversor toothed wheels s-u remaining stationary) with the same speed ofrevolution about their axes, that is about the axes of the shafts w andx.

The torque distribution is calculated as follows:

A state of equilibrium prevails, if-

where S is the force acting at the peripheryof the bevel wheel s and Uis the force acting at the periphery of the bevel wheel u.

.On the other hand the torques Mw and Mx to be transmitted to the shaftsw and a: respectively are:

where Mw is the torque exerted by the force S with the lever arm rt onthe shaft w and M): is the torque exerted by the force U with the leverarm rv on the shaft :12.

From this is obtained the torque ratio at'the shafts w and :c:

Mlihgriagzb M, Ur. r. r. 1,1,

M..:l\l,=cot 112001; B The torque transmitted by the shaft m to thedifferential gear (112 thus distributes itself unequally to the shafts wand a: in the ratio of the cotangent of the angles and B orapproximately in the inverse ratio of these angles, that is to say therear axle is driven by the shaft :0 in accordance with its heavierloading, more particularly by the weight of the driving unit with agreater torque than the front axle by the shaft 10. This distribution oftorque is independent of whether the shafts w and a: turn at the samespeed or different speeds. When the wheels turn at the same speed ofrevolution however there will be no relative motion of the toothedwheels with respect to one another in the differential gear.

At the left-hand end of the differential body dig a claw coupling 3/(Fig. 3) is keyed on, which enables direct coupling of the differentialbody with the shaft w. This causes the action of the differential gearto cease and the shaft m or the differential casing dig and the shafts wand r: are rigidly coupled with one another. In the example shown theshaft w does not directly drive the front axle, but is connected by anysuitable universal coupling 21, with a shaft w and the latter by auniversal coupling 22 with a shaft wz and the latter by a furtheruniversal couplings; with the actual driving shaft wa of the frontwheels. The shaft wa may drive in the usual way the differential gear d1which through articulated shafts vdrives the steerable front wheelswhich are guided independently of one another by two superposedtransverse leaf springs 6.

The drive of the rear wheels is effected directly by the shaft .2: whichextends through the hollow shafts m and l of the gear. The differentialgear d2 is disposed below the engine or coupling shaft h. The rearwheels are mounted for instance on swinging half-axles which swing aboutlateral joints of the casing and are sprung with ,respect to the frame,for instance by unguided helical springs.

If, in place of a differential which distributes the driving torqueunequally to the different axles an ordinary differential gear with anequal drive were provided, it would not be possible, with differentloads on the front and rear axles, to adapt the driving torque to theseloads. But even the provision of a differential gear between each of theindividual axles gives a great advantage in the case of vehicles withmore than two driven pairs of wheels. In certain circumstances thedifferential gear might be combined with a change speed gear in such amanner that the distribution of the driving torque to the front and rearaxle can be changed during operation and consequently a changingadhesive weight of thevehicle can be made full use of.

What I claim is:

A differential gear for power driven vehicles for non-uniformlydistributing the driving torque to a plurality of driven members,comprising two coaxial shafts, a bevel sun wheel on each of said shafts,said bevel sun wheels having substantially the same diameter and facingone another and a planet wheel carrier having "at least one pair ofplanet wheels thereon comprising an outer bevel FRANZ ROLLER.

